The present invention relates to a wheel, on which a tire is mounted and used for vehicles such as an automobile etc., and its manufacturing method, and particularly relates to the adjustment of wheel weight balance.
A tire/wheel assembly, which is used for vehicles such as an automobile etc., includes a wheel and a tire that is assembled onto it. The wheel has an approximately cylindrical rim portion (rim), on which a tire is mounted, and a disk portion (disk), which is fixed to the hub of a vehicle driving axle with bolts etc. Further, an air valve is installed on the rim, which is for pumping compressed air into the tire.
Wheels are generally divided into a steel type and a light metal alloy type such as aluminum alloy etc., and the wheel made of light metal alloy has an advantage that the lightweight tire/wheel assembly can be achieved.
In this type of wheel made of light metal alloy (hereinafter referred to as wheel), drawing is given to the raw product manufactured by forging or casting to form the disk portion and rim portion, and the dimensional refinement is performed by cutting. Cutting has been performed with a center hole as central axis, to which the hub of a vehicle axle is fixed. This is for aligning the central axis of the wheel with the vehicle axle so that the vertical vibration during the vehicle running may be prevented.
An adjustment of shape and weight balance is performed for the tire/wheel assembly during the assembly to achieve the running stability of the vehicle. After the tire/wheel assembly is completed, having the maximum point of the tire strength (RFV point) meet the minimum point of the wheel radius (RRO point), balance weights such as lead etc. are attached on the wheel rim portion as required by checking the balance with unbalance measurement equipment. The amount and position of balance weight have been determined by measuring the unbalance amount and its distribution with a balancer.
However, the wheel above mentioned includes the heavy point position and the unbalance amount, which vary from one wheel to another due to the machining tolerance of cutting, in addition to the weight unbalance of the raw product itself. In this connection, the machining tolerance stems from the offset between the rotation axis of a chuck and the central axis of the wheel raw product, which is attributed to the chuck performance of the cutting machine and is difficult to cancel out to null. Therefore, the balance measurement and the calculation of the balance weight and its mounting position have been necessary for each tire/wheel assembly in the tire/wheel assembly process, resulting in a cause to hinder the improvement of the assembly work efficiency.
It is therefore an object of the present invention to provide a balance adjusted wheel and its manufacturing method, which enable the improvement of work efficiency of the whole process from the wheel manufacturing through the completion of tire/wheel assembly, by adjusting the position of the heavy point in terms of the static weight distribution during the wheel manufacturing process to improve the efficiency of the balance adjustment of tire/wheel assembly.
According to an embodiment of the present invention, there is provided a manufacturing method of balance adjusted wheel, which is a manufacturing method of wheel with a cutting surface, wherein cutting performed by setting the point as a rotation center offset from the central axis of a wheel central portion, which is for aligning the wheel with the central axis of a vehicle axle.
According to an embodiment of the present invention, there is provided a balance-adjusted wheel, wherein at least one of rotation centers of the cutting surface is offset from the central axis of the wheel central portion, which is for aligning the wheel with the central axis of the vehicle axle.
Cutting the wheel by setting a point offset from the central axis of the wheel central portion as a rotation center will easily form the cut surface with eccentricity. The wheel thus manufactured has the portion of large wall thickness, the portion of small wall thickness or the portion where the center of gravity is located offset from the central axis of the wheel central portion, as a result of the wheel having such a cut surface. Therefore, the weight balance as a whole wheel will vary in the known offset direction, which can be utilized for the balance adjustment of the wheel.
The wheel thus manufactured makes the heavy point position and unbalance amount known in advance and is able to reduce the dispersion in them, enabling an efficient balance adjustment work in the manufacturing of the tire/wheel assembly. If the air valve mounting hole that is for mounting the valve to pump up a tire is placed on the line, which is defined by the heavy point thus formed and the center hole, it will be easier to check the heavy point.